1. Field of the Invention
The present invention is concerned with a process for polymerizing or copolymerizing olefins using an improved catalyst. More particularly, it relates to a process for preparing polyolefins which comprises polymerizing or copolymerizing an olefin using an improved catalyst obtained by supporting a solid carrier selected from the group consisting of a reaction product A obtained by reacting (1) an organic carboxylate salt of magnesium and (2) an aluminum compound represented by the general formula Al(OR).sub.3 wherein R may be same as or differnt from each other and each R is an organic radical containing from 1 to 20 carbon atoms under a condition that the aluminum compound is present in excess of a (2):(1) molar ratio of at least 1.6:1 and a reaction product B obtained by treating said reaction product A with a halogenating agent with a titanium compound and/or a vanadium compound followed by activation with organometallic compound(s), especially with an organoaluminum compound and/or an organometallic compound.
2. Description of the Prior Art
Heretofore in the technical field of this sort, it is known that systems composed of a titanium or a vanadium compound combined with an organometallic compound from metals of Group I-III in the Periodic Table can be used as an excellent catalyst for the polymerization of olefins. However, as the catalytic activity in the production of polyolefins is desired to be as high as possible, most of the aforementioned catalyst systems being relatively low in polymerizing activity should desirably be improved. On the other hand, it is also known that catalyst systems prepared from a carrier of a magnesium compound such as magnesium oxide, hydroxide or chloride with a component of Ziegler catalyst, namely, a titanium or vanadium compound supported can be superior catalyst for the polymerization of olefins. In this respect, attempts have recently been made of employing various metal compounds including magnesium ones.